The influence of δ-(Al,Fe)OOH on seismic heterogeneities in Earth's lower mantle.

ABSTRACT: The high-pressure phases of oxyhydroxides (δ-AlOOH, ε-FeOOH, and their solid solution), candidate components of subducted slabs, have wide stability fields, thus potentially influencing volatile circulation and dynamics in the Earth's lower mantle. Here, we report the elastic wave velocities of δ-(Al,Fe)OOH (Fe/(Al + Fe) = 0.13, δ-Fe13) to 79 GPa, determined by nuclear resonant inelastic X-ray scattering. At pressures below 20 GPa, a softening of the phonon spectra is observed. With increasing pressure up to the Fe³⁺ spin crossover (~ 45 GPa), the Debye sound velocity (v_D) increases. At higher pressures, the low spin δ-Fe13 is characterized by a pressure-invariant v_D. Using the equation of state for the same sample, the shear-, compressional-, and bulk-velo

SUBMITTER: Ohira I 

PROVIDER: S-EPMC8187711 | biostudies-literature | 2021 Jun

REPOSITORIES: biostudies-literature